The present invention has particular application to the removal of ammonia from high pressure, high temperature ammonia laden waste or products streams. Such streams are encountered in a variety of processes, including those involving wet oxidation. For example, U.S. Pat. No. 4,792,408 discloses a method and apparatus for enhancing chemical reactions at supercritical conditions. That patent teaches that the speed and efficiency of many chemical reactions can be increased by subjecting the reactants to increased temperature and pressure conditions. This produces a fluid products stream having high temperature and pressure, and, as known in the art, a stream which is often laden with ammonia. U.S. Pat. No. 4,792,408 is incorporated by reference herein for whatever disclosure is necessary with respect to an exemplary wet oxidation method and apparatus.
It is environmentally beneficial, and often required for regulatory purposes, that ammonia be removed or substantially reduced from waste and products streams before final disposal. To this end, it has been known to gas-strip ammonia from such streams. Several factors influence the solubility of ammonia in water, and hence the efficiency of the gas separation techniques, including temperature, pressure, pH and the area of contact between the stripping gas and the liquid.
When stripping or scrubbing a gas such as ammonia from a liquid, it is known that the greater the area of contact between the stripping gas (such as air) and the liquid, the greater is the efficiency of the removal of the ammonia from the solution. One method of increasing the area of contact has included a series of baffles wherein the fluid stream cascades over the baffles.
For a general discussion of gas absorption, such as ammonia stripping, see Chemical Engineer's Handbook, Perry, ed., McGraw-Hill Book Company, pg. 668 et seq. (1950) which is hereby incorporated by reference to the extent necessary for an understanding and disclosure of gas absorption.
The pressures above a liquid having a gas dissolved therein, directly influences the solubility of the gas in the liquid. The lower the pressure, the lower the solubility. The stripping of ammonia at pressures lower than ambient is known in batch processes. Continuous stripping processes are known, and have included spraying the fluid onto the top of a packed tower with trickle down and gas counterflow, and further using a closed loop gas flow to reduce the risk of environmental contamination. The trickle down, closed loop systems heretofore known in the art, have been slow passive processes because there is still a need to remove the water vapor from the gas loop.
Therefore, there is a need for a fluid treatment process and apparatus for the continuous, active treatment of a fluid products stream.